Toluene process



J. QBAILIE `E1' AL TOLUENE rnocnss Filed Aug.,"r. 1942 ou: s, 1946.

vprocess of converting y naptha into aromatic hydrocarbonswhich pro-Patented Oct. 8, 1946 UNITED- sTATEs PATENT OFFICE f Y fL2,408,724.L7''A 1 y 7 l f i e TOLUENE PROCESSrl James C. BalieandRodney V. Shankland, VChicago.' Ill., assignors to Standard OlCom'pany,Chicago, Ill., a corporation of ,Indiana vApplication August 7,1942se1f`ialjNq.. 4535929 sion temperatures and in the presence of hy-vdrogen, employing for the purpose a catalyst which lwe have discoveredto be unusually eiiective for producing toluene. i

"zV claims. (c1. l.stof-ccs)l has .beenw possible* heretofore.

As a result .the amount of toluene which can be produced in a giveninstallation using our improved toluene directive catalyst can be two tofour times the amount obtainable in the same time with cat' alystsheretofore employed.

It has been -known heretofore that catalytic treatment of petroleumhydrocarbonsunder cer-v tain conditions will produce aromatichydrocarbons from hydroaromatics and parafiins. The aromatichydrocarbons thusproduced range all the way lfrom benzene thru theXylenes, higher alkylated benzenes, napthalene and'other condensed ringaromatic compounds. Because of the extraordinary demandfor toluene inthe manu-V facture of explosives, it has become urgently Yirri'jportantto produce the maximum amount vof toluene instead of other lessVdesirable aromatic hydrocarbons such `as' benzene and Xylene. Theprocesses employed hereto-fore for convertingi'petroleum napthas toaromatics have failed to yield morethan about-'10 to 15% of toluenebased on the petroleum hydrocarbon treated when processing Mid-Continentlight napthas using Yconverti-f tional commercial operating" conditions.Furthermore, the catalysts prevrviouslyv employed `became deactivatedrather rapidly especially `with respect to their toluene-producingability. vAsa result of their relative instability the toluene-`vproducing capacity averaged lthruout the life of those catalysts waseven considerably less than these figures would indicate. Incontrasttojthe priorA processes, ourv process has`v produced u,

19-20% of toluene from a selected naptha fraction which is a tolueneyield 25% greater than has been producible by other processes.

One object of our invention isto provide a toluene process and catalystfor converting per Our process is illustrated by a drawingwhichaccompanies the specication and whichmshows diagrammatically anapparatus for carryingout the process.v v

Referring to representsy a prefractionator l,

the drawing, the apparatus'shown a catalytic reactor 2 andfafteri'ractionators 3 and `4. Heattroleum napthas into toluene with a higherdegree of conversion than processes known heretofore. Another objectiswto provide a catalyst with rgreater stability, particularly stabilitytoward the high temperatures employed in catalyst regenv eration,*therebyy producing a higher level of toluene conversion over the lifeof the catalyst. Another object of our invention `is to provide a aselected petroleum reagents.A A still further object of our invention isto provide a catalytic process for making toluene in which thetoluenefproducing activity of the catalyst is suiciently high to enablethe `process to be operated atmuch higher capacitiesl than ers 5 and 6maysuitablybepipe heaters in which coilsoftubing'are placed,v within afurnace setting and the material heated is forced thru the coils. y v jThe stock employed for our pioces's isV .preferably a close-cutstraight-run naptha fraction from 'crude petroleum, but we mayv alsoemploy cracked napthas and"v particularly cracked napthas of lowunsaturati'on from thermal lor catalytic cracking.y YTher napthaspreferred for our process are those containinga high concen-A trationofcycloparafnic hydrocarbons and more particularly `hy'iroarornatichydrocarbons. .ln order to obtain the best yields of toluene wev preferto employ a naptha fraction having aboiling range embracing 4the boilingpoint of toluene, e. 232 ET.;4 A fraction .having initial and iinalboiling points within 25F. of the boilingupoint of toluene is verydesirable and it is undesirable to employ` a napthafractionhavinginitial and final boiling points more thanA about 50 F.away from vthe boiling point of toluene. Aj light naptha fraction havingan vinitial boiling point of about 180 F. and a final boiling point ofabout 280 F.

` is characteristic of the widest hydrocarbon fraction, which it isydesirable to subject to catalytic treatment by our process. vSince poorfractionation will often produce la considerable variation in theinitial' and nal boiling points, it is somewhat preferable v.to controlthe/boilingy ran'geof the naptha by the 10% and9`0% points, ASTM. Anaptha having a 10% point of1 200 F, or above and a 90%, point of: 250F. or below is verysatsjfactory. 1

. Referring to the 'drawingpetroleum napthaor y gasoline is charged tothe process by line I0 and vaporized in coil Il of' furnace 5. Thevap'ors'are conducted by transfer line l2 toy fractionator l where heavynaptha is discarded as a residue by line I3, while light. hydrocarbonsundesirable for our process are withdrawn by vapor line lill. Thedesired naptha fraction is trapped out of the column by line t5 leadingto stripper iE wherein further fractionation takes place-andvundesirablylight hydrocarbons are returned to the main desired fraction, from about200 column by vaporili-ne l1. The yfor example a fractionvboiling iswithdrawn by vapor line 30.

to 260 F. is`withdrawn by line I 8 and forced thru heater 6 where it isheated in coil I9 to the desired conversion temperature or somewhatabove. The hot hydrocarbons are conducted by transfer line 2l] toreactor 2. Hydrogen may be charged to the process by line 2 I, andhydrogen-containing gas may be recycled by line 22 and coil 23 'I'heamount of hydrogen is suitably about 1 `to 5l mols per mol ofhydrocarbon treated and, in general, about 3 mols of hydrogen is asatisfactory amount. This corresponds roughly to `2500 cubic feet perbarrel of naptha. The hydrogen may be introduced directly into thenaptha fraction and simultaneously heated with the naptha in coil I9, orit may be separately heated and introduced into the oil orv.directlyinto the reactor 2.

Reactor 2 is charged 'with the catalyst in granular or pelleted form.The hydrocarbons pass downward thru the catalyst bed and the converted`products may be withdrawn by linev 24. Other methods of contacting thenaptha with the catalyst may rbe employed without departing from ourinvention. For example, the catalyst may be supplied in the form of apowder and maintained suspended in thereaction vessel. In this case,deactivated catalyst maybe withdrawn as a uid from time-to-time orcontinuously regenerated and returned-to the system.

Reactor 2 .is preferably operated under pressures of the order of 50 to500 p. s. i., anda temperature preferably vin the range of 900 to 1050F. Somewhat lower or higher temperatures may be employed, e. g.temperatures as low as 850 li'.y may be employed with low spacevelocities and temperatures as high as 1100o F. may be maintained with,high space velocities.

The space velocity employed is usually within the range .of about 0.1to5 volumes of naptha per hour per gross volume of catalyst, a spacevelocity of 0.5 to 2 being most commonly employed. The volume of napthareferred to in indicating the space velocity is the liquid volume of thenaptha charged at standard temperature conditions, while the volume ofcatalyst referred to is the gross volume occupied by the catalyst, notthe net volume of the catalyst ywhen corrected for voids. It should beunderstood that the amountfof toluene produced can be generallyincreased by operating at. lower space velocities and/or higher`temperatures, but that in general vgas losses are increased at the sametime. vWhen using our toluene directive catalysts it is possible toeffect conversion at reasonable space velocities, for example, 1 to 2 V.H. V. producing high yields of-toluene with only moderate gas losses. "l

The reaction products from 2.pass, by line 24, thru cooler 25 and thenceby line 2S to gas separator 21, thence to fractionator 3 wherein a heavyaromatic fraction is separated and with- .drawn by line 28. This heavyfraction, substantially free of toluene,4 may beemployed in themanufacture of motor fuels, aviation gasoline, etc., for example byblendingl with the naptha fractions eliminated in fractionator I bylines I 3 and I4. It may also be used as a solvent in paints, varnishes,etc. taining substantially al1 of the toluene produced is withdrawn as aside stream by line 29. A crude light fraction substantially free oftoluene Fixed gases including hydrogen are withdrawn from separator 21by line 3l and recycled by blower 32 and line 22 back to the reactor,preferably after being A lighter fraction con-A outlet a4.

4, heated to reaction temperature or above by heating coil 23 located infurnace 6, as vpreviously described. The amount of gas recycled in thisway depends on the net gas production, the hydrogen concentration of thegas and other factors. Excess gas may be withdrawn by valved Thisrecycle gas may be enriched with respect to hydrogen content byincluding an absorber (not shown) in the recycle system to remove lowboiling hydrocarbons and thus raise the hydrogen concentration in therecycle gas.

The crude toluene fraction is conducted by line 29 to fractionator `4-which is preferably an enicient fractionating tower with a large numberof plates. In this tower the, toluene is withdrawn as a side stream bytrapout line 35 leading to stripper 36, the vapors being returned to themain tower by line 3l, while the toluene is Withdrawn from the ysystemby line 38. On account of the presence of a small amount of paralinichydrocarbons boiling near the toluene boiling point, it is notpracticable to recover all the toluene from the products by fractionaldis- `I thru lines I3 and I4.

tillation. Therefore, in practice the amount of substantially pure,nitration grade toluene recovered from the c-rude toluene fraction isabout '7D-80 percent. ySome additional toluene and close-boiling paranichydrocarbons are. present in fractions boiling just above vand justbelow the toluene boiling'. point. Ay heavier fraction is withdrawn as acondensate from fractionator 4 by line 39 and recycled by line 40 to theconversion step.

Hydrocarbons boiling `below toluene are withdrawnas a vapor stream byline 4I and further fractionated in fractionator 42. Substantially allthe toluene carried away with the light products is collected as acondensate in the base of fractionator 42 whenceV it is conducted byline `43 back to the conversion step of the process. Benzene and otherlight hydrocarbons are withdrawn by line 44 to condenser `45 andreceiver 46, whence they are discharged by line 47. Parafns may berecovered from this fraction by further fractionation and/or chemicaltreatment or the benzene fraction may be employed in the manufacture ofhigh knock rating motor fuels, aviation gasoline, etc., for example byblending with the naptha fractions eliminated in tower The tower 46 isvented byline 48.

In recycling the fractions bordering on toluene, i. e. the stocksrecycled thru lines 39 and 43we obtain, in effect, a catalyticpurication of this intermediate material from which it has heretoforebeen diicult to recover the toluene. The toluene contained thereinpasses thru the catalytic reactor 2, substantially unchanged, whilenon-aromatic hydrocarbons boiling near the boiling point of toluene areconverted into additional toluene and/or other products of diierentboiling points by the action of the catalyst. Some alkylation ofrecycled benzene also appears to take lplace in reactor 2, therebyforming additional must be removed. This is accomplished by passing anoxygen-containing regeneration gas thru the catalyst. The stream ofnaptha entering reactor 2 is interrupted or diverted and air or otheroxygen-containing gas is introduced by line v49 under carefullycontrolled conditions to pre'- y asesoria.

Whatever. This desirable result has not been posn siblewith catalystsemployed heretofore because of the relatively larger amount ofnon-aromatic hydrocarbons occurring in the products, having boilingpoints close to the |boiling point of toluene land inseparable therefromby fractionation. The use of our new catalysts has made it possible forus to produce nitration grade toluene directly from the catalyticconversion process with no decrease in toluene yield but with evengreater yield than obtainable by the previous processes. The toluenefraction may be submitted to additional purification'by extraction witha-selective solvent, by extractive distillation using a solvent such asphenol, nitromethane, etc., or by a chemical treatment when desired toprepare the toluene for. some special purpose. v

The catalysts lwhich we-employ rand which We term toluene directivecatalysts are comprised of aluminum oxide of high purity promotedwithmolybdenum. They may' 4be prepared conveniently by dissolving metallicaluminum under conditions to produce an alumina sol, after which the solis converted to alumina gel. In forming the dry gel from the sol vit isdesirable fto kcoagulate thesol to a firm, solid, vibrant jelly which isdried and ignited as will be described hereinafter. The lalumina ispromoted'with molybdenum whichmay be applied either before or after theformation ofthe gel, the latter method. producing .a moretoluene-directive catalyst.

Another method'of preparing our'specially pure aluminum oxide catalystis by precipitation `of aluminum hydroxide from aluminum salts .of highpurity followed by extensive `washing-1 untilthe Wash water shows noqualitative testfor vextrane- 'ous'metals, particularly metals of theiron group and the alkali metals. On account of thegel'att- Vnous natureof aluminum hydroxide it has heretofore been substantially impossible towash extraneous metals therefrom completelyapparently because of theircolloidal adsorptive retention.

We have found that if the aluminum hydroxide y A obtained onprecipitation is solidly frozen paste and thereafter thawed, thegelatinous character is largely destroyed and Washing is greatlyfacilitated. After complete removal 'of extraneous metals thealuminaobtained in this way is dried land ignited, and the molybdenum promoteris added. I

For the purpose just described, aluminum hydroxide may be precipitatedfrom aluminum chloride, aluminum nitrate, aluminum sulfate, or

other soluble aluminum salt, by the addition of ammonia to the saltsolution.

The catalyst may be prepared from metallic aluminum by the methoddescribed in U. S..Patent 2,274,634. The general procedure involvedrequires amalgamation of the aluminum metal, for example aluminum intheforrn of .foil or granules is amalgamated andconverted into analumina sol in the presence of diluteacid. A Weak organic acid such asacetic .or formic acid at a concenignition" step,

.added in solution.

accumulation of carbonaceous deposits.

.mentioned hereinabove. ytion `gas containing a relatively small amountof oxygen, e. g. 1 to 5 percent, facilitates the opera tration-cfabout 1te 6 percent is satisfactory, Other vslealt` acids may be -used such ascitric, ehloroacetic.. etc., Y

The amalgamation may be vaccomplished. ,by addingapmercury salt ormercurio oxide :to the acid solution before adding the aluminum. Rapidsolution of the metal takes place withthe formation of -asol which inthe case of Aformic acidis more iluid .than that. obtained with aceticacid. Thesol be coagulated by adding an electrolyte such aszammoniumycarbonateand in the case of more highly concentrated sols,coagulation-may occurspontaneously when standing or on 'heating- Thecoagulatedrsolis then dried slowly in a current .of warm, dry air andthe dried alumina is ignited, for example by heating to a temperature of.about-1100?J F. .and Aholding at that temperature about twenty-four toforty-.eight hours. Organic acids adsorbed on the alumina produceacertain amount of carbonization on heating, and carbon so .producedis`burned away by air during the care being taken to lcontroltl'ie :rateof burning to avoid overheating the alumina and impairing its 'catalyticactivity. Where formic acid is usedin preparingthe sol, carbonization isminimized..

As indicatedhereinabove, themolybdenum-promoter may be Aadded to thealumina during preparation or after ignition and we have iound .thatwhen the promoter is added after ignition the resulting catalyst is.more khighly directive for the formation of toluene `.than when thepromoter is added before ignition, for example while the alumina isinthe sol form. Thusin comparing two catalysts, one in which themolybdena is added to the valumina sol, and the other in which the`molybdenais added to `the ignited alumina, we find tha-t whereasthearomatization lcharacteristics are Ysubstantially the same, eachcatalyst producing apprexi-mately the same amount of aromatics, thedistribution -of aromatics is quite different, the alumina promotedafter ignition giving a higher yield of toluene. The explanation of thisphenomenon is not understood.

The amount Vof promoter employed is usually about 5 to l0 percent ofmolybdenum oxide `'based on the weight of the catalyst and We may usesomewhat greater amounts., for example 15 to 20 percent'. A convenientway of applying the promoteris by means of the ammonium molybdate saltwhich iseasily water-soluble and may be Thus when applying themiolybdena to purealuminum oxide ignited at 800 to 1100 F., thekammonium molybdate solution can be applied directly to the alumina,which is then dried and reignited.

After 'preparing the catalyst as hereinabove described, we prefertogrind it to approximately 30 to 100 mesh and vpellet the resultingpowder in a suitable pelleting machine. An organic binder such as rosin,stearine pitch, etc.,'may be employed for this purpose, kthe binderbeing removed Subsequently by heating and ignitine.

After operating our process for a period of hours, for example one, totwenty hours, the activity of the catalyst becomes impaired by an Six'hours is a convenient..time of operation. It isy then necessary tointerrupt the conversion oper- -ation and regenerate the catalyst bycontacting it with air or other oxygen-containing gas, as

The use of regeneration.;:Qontrol-.of,regeneration is improved byretaining the catalyst in small diameter tubes surrounded by a coolingmedium." After regeneration the catalyst is ready forfurther contactingof hydrocarbon vapors and it may be reused and regenerated an indenitenumber of times. An outstanding characteristic of our catalysts madefrom pure alumina is their high thermal stability. Thus we have foundthat the catalytic activity actually increases in use for a period oftime before it reaches a constant activity level where it remains 'for along period of time.

The following data show the results obtained in the production oftoluene by our process:

A Mid-Continent straight-run light naptha having a boiling range of 196to 258 F., and A. S. T. M. distillation shown in the table, was treatedwith a catalyst prepared in the following way: Amalgamated aluminum wasdissolved in acetic acid beginning with about 1 per cent concentrationand later adding additional acid to bring :the concentration to 2% asthe aluminum` dissolved. The resulting alumina sol containing about 6%of A1203 congealed to a solid jelly on standing. 'Ihe jelly was driedand ignited for twenty-four hours at 1100 F. It was then treated withammonium molybdate solution, dried and further ignited at 1000 F., 9percent molybdenum oxide being impregnated in the catalyst in this wayInspection of Mid-Continent light 'naptha feed stock Gravity A. P. I61.0 A. S. T. M. distillation, F.: r

Initial 196 10% 208 211 30% 213 40% 4216 50% 219 60% 222 70% 227 80% 23190% 239 End point 258 Analysis:

Aromatics, v01. per centl Benzene' 0.3 Toluene 2.2 Xylenes 0.7

Total 3.2

Napthenes, vol. per cent- Initial, 205 F 12.9 205-228 F 13.1 22S-255 F12.7 255-270" F 2.2

Total 40.9

Parafns, vol. per cent- Initial, 205 ,F 22.3 205-228 F 11.8 22S-255 F16.1 Z55-270 F 4.3

Total 54.5 Residue (not examined) 1.4

The naptha referred to was passed in a stream thru the catalyst under apressure of 200 p. s. i.

of naptha treated. The following results were obtained as an average ofthree successive sixhour reaction periods with the same catalyst,regenerating the catalyst between runs, and as an average of tworeaction periods at about double the space velocity. Data obtained witha commercial catalyst are included for comparison.

Alumina gel Commercial catalyst catalyst Aver- Aver- Aver Average of ageof age of age of 3 runs 2 runs 7 runs 2 runs Temperature, F 985 970 978978 Space velocity l. 00 v 2.01 0. 94 l. 9 Yields, output basis:

Vol. per cent liquid product 56. 0 6:1 6 73. 3 83. 7 Wt. per cent drygas 39. 1 32', l 23. 1 13. 5 Wt. per cent carbon 0, 32 0.14 0. 18 0.1Gravity of liquid product 45. 3 48. 0 52. 6 55. 4 Toluene, vol. percent:

In liquid product 34 25. 2 21. 3 15. 5 L1 cui 204255 F 97. 8 79. 8 59. 435. 0 Yield based on naptha feed 19. 0 16. 0 1.5. 6 l2. 9

The commercial catalyst was an Activated Alumina containing about 9% ofmolybdenum oxide. It will be vseenfrom the data that at a space velocityof about 1 our improved catalyst shows an increase in toluene productionfrom 15.6 to 19% which is approximately22%. At the higher space velocityof approximately 2, the increase was from 12.9 to 16%, exactly'24%increase.

'Still more striking is the toluene concentration in the fraction 204 to255 F. This figure gives an indication of the completeness of theconversion of'parafiln's and napthenes to toluene. At approximately unitVspace velocity the toluene purity'in this fraction increased from 59.4to 97.8%, almost double, while at the higher space velocity ofapproximately 2, the increasek was more than double.

Another catalyst was prepared from amalgamated aluminum in the same Wayas thatl'ust described except that the alumina sol was coagulated by theaddition of ammonium carbonate and ammonium molybdate, sufficientammonium molybdate solution being added to the sol to provide a catalystcontaining about 9% of molybdenum oxide, M003. The catalyst was thendried and ignited. This catalyst, ywhich may be termed a co-gelledcatalyst, wasA employed with the same naptha under the same conditionsas just described and gave the following results at two different spacevelocities:

Average of Average oi two 6-hr. two -hr. runs runs Temperature 972 975Space velocity 1. 0 1. 99 Yields, output basis:

Vol. per cent liquid product-.. 60. 5 68. 4

Wt. per cent dry gas 35. 1 28. 3

Wt. per cent carbon.; 0. 13 0. 1 Gravity of liquid product API 48. 9 52.2 Toluene, vol. per cent:

In liquid product 28. 5 22. 0

In cut 204-255 F 87. 9 68. 0

Yield based on naptha feed 17. 2 15.1

It will be observed from these data that the catalyst in which themolybdenum oxide promoter is co-gelled with the alumina is considerablyless effective in producing toluenethan the catalyst in which'substantially the same alumina was promoted with molybdenum oxide,applied subsequent to ignition of the alumina. The total aromaticsproduced by the two catalysts were found to be substantially the same.Apparently the toluene-directive raction ofthe catalyst isk considerablyinfluenced by the method of adding the' promoter element, the toluene`production being improved by `adding thepromoter to the alumina afterignition. An examination ci the data just presented shows .17.2% averageyield 'of toluene from the co-gelled catalyst and 19% from the'catalystpromoted after ignition, an increase of 10.5% in this case, operatingunder the same conditions with the same. spacevelocity.H Space Velocityis the volume lof'liquidnaptha per hour charged per gross volume ofcatalyst. Thus if two barrels of naptha are charged' per hour thru onebarrel of catalyst, the space velocity is 2. f

I n order to determine the chemical changes occurring in the catalyticprocess, we made anvalyses of the products obtained from two runs madewith the best commercial catalyst avail ableand two runs made with' theimpregnated alumina gel catalyst from amalgamated aluminum. Productsobtainedv from runs made at two different space velocities,approximately 1 and approximately 2, were tested. The conditions were980 F., 200 p. s. i., and 6-'hour reaction Vperiods with about 2500cubic feet of hydrogen per barrel. The results are shown 1n thefollowing table: f

Naptha.. Aluginma Coirliery (feed) catalysty catalyst Spacevelocity,-Vn/h'r./Vc 2.01 1.00*v 1.90 094- vYields basedon feed:

Carbon Wt. per cent.. 0. 14 0. 19 0.10 0. 16 Dry-gas .do-.' 25.5 33.110.'8 20.9 C415.; per cent 9.7 11.8 3.0 6.3 CsS .d 6.5 7.3 4.4 4.71Z0-204 F Benzene...V ..`.-..do'. 0.?.l 3.1 4.4 2.3 3.1 `Napthenesandparalns per sente. 35.2 10.2 3:3 28.2- 22.41

204-255212: I W v l,

Toluene .-.do 2.2 y16.0 19.0 13.0 15.8 Napthenes and paralnns r percent-. 53.7 4.1 0.4 23.2 A10.7 v255300 F.: l f A .n I

A Xylenesnegi.;li..;.;do..i. 0.7 12.7 11.6 11.0 11a-9 Napthenesandvparains l A.

Y y percent.. `6.5 0.2 0 1.2 0.5 Above 300 F.: 2 i y Higher aromatics dol A Higher napthenes-l-para- 1.4 2.9 2.6 1.5 1.6

liins. ..v .:per cent..

1 255-270 F. in case of feed. 2 Above 270 F. in case of feed.

Norm- Percentage is by volume except Where indicated. n

As indicated hereinabove, we prefer to lprepare our toluene directivecatalyst from metallic aluminum, rst forming an alumina sol, then a gel.Metallic aluminum of high .purity should be used for lthis purpose. Allreagents should be substantially free of other metals except the desiredpromoter and We have found that the alkali metals in .particular areobjectionable. The catalyst m-ade from aluminum metal is .substantiallyfree of sodium, containing not more than about .01 percent of thiselement. We prefer that the alkali metal content of our .catalyst be notmore than 0.1 percent.

If the alumina is prepared by precipitation from an aluminum salt, it isimportant to employ an aluminum salt, for example aluminum nitrate,

which is substantially free of alkali metal salts. This objective may beattained'readily when sublimed aluminum chloride is employed forpreparing .the catalyst. The use of distilled Water and glass, wood orceramic mixing vessels in making up the catalyst is importanti-,oprevent contamination.

Having thus described our invention what.' we claim is:

1. The process of making toluene in high concentration from petroleumnaptha which comprises contacting said naptha at a lconversiontemperature Within the range of about 850 to 1100" F. with a catalystsubstantially free of alkali metals consisting essentially ofaluminavgelpromoted-withabout 5 .to 10 per cent of molybdenum oxide, theboiling range of said naptha lying within about 50 F. of the boilingpoint of toluene, supplying t'o the reaction zone about 1 4to 5 mols ofhydrogen per mol of naptha treated and re, covering toluene from thereaction 4products,sa.id alumina gel having been prepared by dissolvingamalgamated metallic aluminum in a weak acid thereby forming an aluminasol, gellingsaid sol,

concentration from petroleum which comprises contactingfa napthaboiling-'within .the range of 196 Ito 258 F. at .au temperature of about850 to 1100 F., with an alumina gel catalyst substantially free ofalkali metalsfand impregnated with about .5,.t'ol20 per .-cent ofmolybdenum oxide, maintaining the pressure' Within'the catalytic're'laction zone in the range of about 50 to 500 p. s.i-.f, feeding saidnaptha at -a space velocity of about 0.5 to5 volumes per hour per volumeof catalyst in. .the'reaction zone, introducing 'into `said reactionzone about 1 to 5 mols of hydrogen per mol of rnaptha-1treatedv andVrecovering toluene from the reaction products, said alumina gel havingbeen prepared by dissolving amalgamated metallic aluminum in a diluteorganic acid selected from' the class consisting of acetic and ormicacids, startingthe solution in an acid or about 11% concentration`and=subsequently increasing the'concentration until an alumina solcontaining Vfrom aboutl .to 10 percent A1203 is'fobtain'ed;dehydratingsaid sol tor aluminagel of low moist-ure content, and heatingsaid alumina gel in an atmosphere oi'controlled oxygen content to removeadsorbed organic acid.

4. The process of making .toluene in high :concentration from petroleumwhich comprises contacting, in a reaction zone, a petroleum napthaboiling in the range of 196 to 258 F. with a catalyst consistingessentially of alumina gel promoted with about 5 to 10 per cent ofmolybdenum valumina. gel catalyst having been prepared by dissolvingamalgamated metallic aluminum in a weak acid thereby forming an aluminasol, co-p a'gulating said sol to a rm, vibrant gel, drying and ignitingIthe resulting gel, and impregnating said gel with a solution of asoluble compound of molybdenum which on ignition Will be converted tomolybdenum oxide. 1

5. The process of makingY toluene jfrom .petroleum in high concentrationsufciently free from contaminating non-aromatic hydrocarbons of similarboiling points to permit the recovery of substantially pure to-luene b-ydirectdistillation of the, products which comprises contacting, in areaction zone, at a temperature of about 900 to ,1050 F. a napthaboilingwithin the range of.l80 .to 280 F. With a Catalystconsisting-essentially of alumina .gel promoted with. about to. per centof molybdenum oxide` and substantiallyfree of alkali metals at aypressure of about50to 500 vpounds per square inchand in the presence ofaboutl to5 mols of added hydrogen per mol yof, naptharhydrocarbontreated, charging said naptha to the, catalytic reaction zone at a spacevelocity of about 0.14 to 5.vol urnes of liquid naptha per hourvpergross volume of catalyst in the.k reaction zone, and recoveringtoluene from the reaction products by direct distillation, saidv aluminagel having --been prepared by dissolving amalgamated metallicaluminum ina Weak acid thereby forming `an aluminasol, gelling said sol, drying andigniting theresulting gel, and impregnating saidgel with asolution of asoluble compound of molybdenum which on ignition will ,be converted tomolybdenumoxide. The, process, of, makingtoluene from4 .petroleum inlhigliconcentration suilcientlyfree from contaminating non-aromatichydrocarbons Totsirnilar boiling points topermitthe recovery lofsubstantiallyv pure, toluene by direct distille.,- tionof the productswhich comprises -contacting, in4 a reaction zone,` lat `atemperaturev.of .about 900 to 1050 F. a naptha lboiling.,within the range of 1,80to 280 F. with a catalyst consistingessentially of alumina Vgel promotedWith about 5to 10 ,per cent of molybdenum oXideandsubstantially, freefalkalif metals at a pressure .of about V50u30 5 00 pounds per squareVinch and. inthe presence ofabout 1,to 5 mols lof added hydrogen plmol ofn aptha hydrocarbon treated,.charging Sfd, naptha tothe catalyticreaction zone ,ata

spacelvelocity of. about 0.1 to 5 volumesof liquid naptha per hour pergrossvolumeof catalyst in the reaction zone, and recovering toluenefromthe reaction products byV direct distillation, said alumina gelcatalystA having been prepared by dissolving amalgamated metallicaluminum n a weak acid to form an alumina sol, then jgelling the sol byadding a solution of electrolyte, drying and igniting the resulting gel,and impregnating said gel with a solution of a soluble compound ofmolybdenum which on ignition will be converted to molybdenum oxide.

7. The process of making toluene of high' concentration from petroleumwhich comprises contacting a petroleum naptha boiling Within. the rangeof 180 to 280 F. with a porous solid catalyst consisting essentially ofalumina gel prepared by dissolving amalgamated aluminum metal in a weakacid, gelling the resulting sol, drying and igniting the resulting geland promoting it with about 5 to 10 per cent of molybdenum oxide byimpregnating it With a solution of a molybdenum compound which onignition will be converted to molybdenum oxide, then igniting saidimpregnated gel, maintaining a space velocity Within the range of about0.5 to 5 volumes of naptha per hour yper gross voluime of catalyst inthe reaction zone, maintaining the reaction temperature at about 900 to1050 F. and a pressure of about to 500 pounds per square inch, supplyingto the reaction zone about l to 5 mols of hydrogen per mol of napthatreated, fractionating 'the reaction products into a substantially puretoluene fraction,y a heavy substantially toluene-free Xylene fraction, alight substantially toluene-free benzene fraction, kand at least oneintermediate boiling fraction containing toluene and non-aromatichydrocarbons boiling close to toluene, recycling said intermediateboiling fraction to said catalytic conversion step, thereby convertingsaid non-aromatic hydrocarbons into aromatic hydrocarbons and productshaving boiling points less close to the boiling point of toluene thanthe boiling point of said non-aromatic hydrocarbons in said intermediatefraction and subsequently separating said lastmentioned products fromtoluene in said fractionation step.

` JAMES C. BAILIE.

RODN'EY V. SHANKLAND.

